Weston Mills (variant names Westons Mills and Weston’s Mills) is a hamlet in the towns of Portville and Olean in Cattaraugus County, New York, United States. It is counted as a census-designated place by the U.S. Census Bureau, which recorded a population of 1,472 at the 2010 census.

Weston Mills was founded by the Weston family, three brothers who set going on the titular mill in the community. According to county administrator Jack Searles, the make known was likely either Weston’s Mills or Westons Mills at first (the 1869 Beers Atlas uses the name “Westonville” for the location), then distorted to Weston Mills at the behest of President Benjamin Harrison, who sought to standardize post-office names by removing unnecessary possessive forms (see United States Board upon Geographic Names). The “s” was slowly, and colloquially, restored more than the course of the 1960s, after a store (now Carpet Town Carpet One / Ashley Furniture HomeStores) opened using the “Weston’s” name. The indigenous Weston relatives homestead is now owned by the government, which operates it as a bureau home.

Westons Mills is located at 42°4′13″N 78°22′44″W / 42.07028°N 78.37889°W / 42.07028; -78.37889 (42.070296, -78.379012). It is primarily in the town of Portville, but extends west into the town of Olean as far as the limits of the city of Olean. New York State Route 417 passes through the community, leading west 2 miles (3 km) into the middle of Olean and southeast 3 miles (5 km) to the village of Portville.

According to the United States Census Bureau, the CDP has a total Place of 6.8 square miles (17.5 km), of which 6.7 square miles (17.3 km²) is home and 0.08 square miles (0.2 km), or 1.09%, is water.